The present invention relates to creeper for supporting and carrying a worker in places of restricted clearance such as under vehicles, building structures and the like, where a variety of ground surface conditions may exist.
Conventional mechanics' creepers have a rectangular platform equipped with a head rest, the platform being supported at minimal ground clearance on three or four casters, or a combination of wheels and casters. While the conventional creepers are suited for pristine conditions found in many workshops and on concrete driveways, they are awkward to use or entirely impractical on uneven and unstable surfaces commonly found under mobile homes and at roadway shoulders, for example. Particularly, there is minimal ground clearance which is insufficient for avoiding grounding contact by the platform against crests of the terrain and debris commonly found thereon. Also, the wheels of prior art creepers are ineffective for support on soft terrain such as turf, gravel and sand. Instead of providing rolling support, the wheels dig in while failing to roll, the platform sinking to the ground as well, and the user must find other means of protection and/or access.
U.S. Pat. No. 4,185,846 to Black discloses a creeper having a parallel spaced pair of rigid tracks that are rollably mounted to the underside of a platform and are used by an operator for "walking" the creeper along. The creeper of Black has significant disadvantages in that movement beyond the stroke of the tracks is difficult to accomplish, and the creeper has limited turning capability, if any, particularly on hard, flat surfaces. Also, respective sides of the creeper must be lifted high enough for the tracks to extend, unloaded, over uneven terrain. Further, when the tracks bridge across rocks, crests and the like, there is reduced clearance for worker movement. Moreover, firmly anchored rocks and the like that protrude above ground can block turning movements, the turning being prevented until there has been a gross longitudinal movement past such obstacles.
Other creepers are disclosed in U.S. Pat. Nos. 1,649,721 to Mohler, 1,823,526 to Breeden, 4,875,694 to Hamrick, 4,909,524 to Paine, and 5,213,350 to Hermanson. These creepers are ineffective in that they need excessive ground clearance; they employ narrow wheels which have little float or traction in soft turf; they require padding for operator protection from sharp structural protrusions; they are useful only on hard or smooth surfaces; and/or they are not effective in hard or rocky soil.
U.S. Pat. No. 4,792,147 to Wissing discloses a creeper having a molded body, sides thereof extending upwardly about a user's head and torso, and having removable wheels for permitting the body to be slid over rough and unstable terrain. The wheels, being typically 6 inches in diameter and having a width of 2 inches, are attached near the top of the sides and provide a nominal ground clearance of 1 inch when mounted. Larger wheels can be substituted. The creeper of Wissing also has significant disadvantages:
1. There is insufficient ground clearance for rolling over uneven and/or soft terrain with the standard wheels; PA1 2. It is awkward to use in that the high, closely fitting sides impair movement and vision of a user, and the user must get off, remove, and store the wheels when encountering terrain unsuitable for rolling on the wheels; PA1 3. Substitution of larger wheels makes the creeper ineffective for use where clearance is limited, requires separate storage of one or both sets of wheels, and impairs maneuverability to the extent that there is interference between the wheels and the body; and PA1 4. It is believed that the wheels are subject to becoming bogged down, failing to roll on sand.
Aside from the other disadvantages, it is believed that none of the prior art creepers provide effective rolling support on the wide variety of ground surfaces that are commonly encountered in restricted clearance working situations under vehicles, building structures and the like.
Thus there is a need for a creeper that is effective for use in confined spaces, without impairing a user's movement or vision, that is easy to use and maneuver without modification on a variety of surfaces from hard and smooth to soft and uneven.